The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Jun Kimura - One of the best experts on this subject based on the ideXlab platform.
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Prolongation oF F-Wave minimal latency: a sensitive predictor oF polyneuropathy
The International journal of neuroscience, 2015Co-Authors: Nivedita U. Jerath, Edward A. Aul, Chandan G. Reddy, Hamid Azadeh, Andrea Swenson, Jun KimuraAbstract:Introduction: To evaluate the sensitivity oF F-Wave minimal latencies, we compared F-Waves with motor and sensory nerve conduction studies (MNCS and SNCS) in patients with peripheral neuropathy. Methods: A retrospective chart review conducted in 484 patients conFirmed the clinical evidence oF a polyneuropathy, and studies oF F-Wave minimal latencies as well as MNCS and SNCS in each patient. Results: Overall rate oF abnormality reached 469/484 (96.9%) For F-Wave minimal latencies as compared to 374/484 (77%) For nerve conduction studies ( p < 0.0001). Nerve-speciFic abnormalities oF F-Waves showed 290/354 (82%), 140/171 (82%), 367/398 (92%) and 357/376 (95%) For median, ulnar, peroneal and tibial nerves, respectively. Corresponding values For MNCS consisted oF 108/354 (31%), 29/171 (17%), 258/398 (65%) and 189/376 (50%) (all p < 0.0001). In contrast, SNCS revealed abnormalities in 120/333 (36%), 60/159 (38%) and 266/474 (56%) oF median, ulnar and sural nerves. Conclusion: F-Wave minimal latencies serve as ...
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F Wave latencies in patients with diabetes mellitus
Muscle & Nerve, 2014Co-Authors: Hua Pan, Jinxi Lin, Na Chen, Fan Jian, Zaiqiang Zhang, Zeyu Ding, Yongjun Wang, Liying Cui, Chunfang Zhang, Jun KimuraAbstract:Introduction: To evaluate the sensitivity oF electrophysiologic assessments, we compared F-Waves and motor and sensory nerve conduction studies (MNCS and SNCS) in patients with diabetes mellitus (DM). Methods: We tested median, ulnar, tibial, and Fibular nerves in 132 DM patients divided into those with and without clinical evidence oF polyneuropathy. Results: OF 64 asymptomatic patients, 2 (3%) had MNCS or SNCS abnormalities, both oF whom had F-Wave changes, whereas 21 (33%) had only delayed F-Waves, For a combined yield oF 23 (36%). The corresponding values For 68 symptomatic patients consisted oF 43 (63%), 14 (21%), and 57 (84%). In both groups, F-Wave latency had a higher (P < 0.05) Frequency oF abnormality than MNCS in all nerves. F-Wave study also surpassed SNCS in lower limb nerves. Conclusions: F-Waves oF the tibial and Fibular nerves are the most sensitive measure to detect subclinical or overt diabetic polyneuropathy. Muscle Nerve 49: 804–808, 2014
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F-Wave latencies in patients with diabetes mellitus.
Muscle & nerve, 2014Co-Authors: Hua Pan, Jinxi Lin, Na Chen, Fan Jian, Zaiqiang Zhang, Zeyu Ding, Yongjun Wang, Liying Cui, Chunfang Zhang, Jun KimuraAbstract:Introduction: To evaluate the sensitivity oF electrophysiologic assessments, we compared F-Waves and motor and sensory nerve conduction studies (MNCS and SNCS) in patients with diabetes mellitus (DM). Methods: We tested median, ulnar, tibial, and Fibular nerves in 132 DM patients divided into those with and without clinical evidence oF polyneuropathy. Results: OF 64 asymptomatic patients, 2 (3%) had MNCS or SNCS abnormalities, both oF whom had F-Wave changes, whereas 21 (33%) had only delayed F-Waves, For a combined yield oF 23 (36%). The corresponding values For 68 symptomatic patients consisted oF 43 (63%), 14 (21%), and 57 (84%). In both groups, F-Wave latency had a higher (P
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EFFect oF motor imagery and voluntary muscle contraction on the F Wave.
Muscle & nerve, 2010Co-Authors: Motohiko Hara, Shinichirou Taniguchi, Jun Kimura, Thoru Yamada, Hiroo Ichikawa, Reiko Fujisawa, Hiroshi Shimizu, Tatsuya Abe, D. David Walker, Ryoji KayamoriAbstract:We tested the validity oF instructing patients to minimally contract the muscle to Facilitate F-Wave recording in clinical practice. In 12 healthy subjects, F Waves were recorded From the First dorsal interosseous muscle at rest, during motor imagery, and at up to 30% oF the maximal voluntary contraction (MVC). F-Wave persistence increased signiFicantly From 32.5 ± 11.9% (mean ± SD) at rest to 58.3 ± 15.2% during motor imagery and 90.0 ± 8.7% during 3% MVC. It then remained the same during stepwise changes to and From 30% MVC beFore decreasing signiFicantly From 80.8 ± 18.5% during 3% MVC to 48.7 ± 23.8% during motor imagery and 27.0 ± 16.0% at rest. The trial average oF F-Wave amplitude showed a similar pattern oF Facilitation. Motor imagery enhances F-Wave persistence and amplitude, which Further increase with a slight muscle contraction and show no additional change with a stronger eFFort. Muscle Nerve, 2010
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eFFect oF motion imagery to counter rest induced suppression oF F Wave as a measure oF anterior horn cell excitability
Clinical Neurophysiology, 2008Co-Authors: Shinichirou Taniguchi, Jun Kimura, Thoru Yamada, Hiroo Ichikawa, Motohiko Hara, Reiko Fujisawa, Hiroshi Shimizu, T TaniAbstract:Abstract Objective To test iF motor imagery prevents the rest-induced suppression oF anterior horn cell excitability. Methods Ten healthy subjects underwent two separate experiments, each consisting oF stimulating the median nerve 100 times and recording F-Waves From abductor pollicis brevis (APB) in three consecutive sessions: (1) aFter muscle exercise to standardize the baseline, (2) aFter immobilization oF APB For 3 h and (3) aFter muscle exercise to check recovery. We instructed the subject to volitionally relax APB in experiment 1 (relaxation task), and to periodically simulate thumb abduction without actual movement in experiment 2 (imagery task). Results F-Wave persistence and amplitude declined aFter relaxation task and recovered quickly aFter exercise, but changed little with imagery task. F-Wave latencies showed no change when analyzed individually. The Frequency distribution oF collective F-Waves recorded From all subjects remained the same aFter relaxation task, but showed a shiFt toward longer latencies aFter imagery task. Conclusions Mental imagery without overt motor output suFFices to counter the eFFect oF sustained volitional muscle relaxation, which would, otherwise, cause a reversible reduction in anterior horn cell excitability. SigniFicance This Finding documents the importance oF central drive For spinal excitability, which aFFects F-Wave studies oF a paretic muscle.
Kazuhiko Kuroki - One of the best experts on this subject based on the ideXlab platform.
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microscopic theory oF spin triplet F Wave pairing in quasi one dimensional organic superconductors
Physical Review B, 2004Co-Authors: Yukio Tanaka, Kazuhiko KurokiAbstract:We present a microscopic theory oF Fluctuation-mediated pairing mechanism in organic superconductors ${(\mathrm{TMTSF})}_{2}X$, where the experimentally observed coexistence oF $2{k}_{F}$ charge Fluctuation and $2{k}_{F}$ spin Fluctuation is naturally taken into account. We have studied, within the random phase approximation, the extended Hubbard model at quarter Filling on a quasi-one-dimensional lattice, where we consider the oFF-site repulsive interaction up to third next-nearest neighbors along with the on-site repulsion. The results show that spin-triplet $F$-Wave-like pairing can be realized in this system, dominating over singlet $d$-Wave-like pairing, iF $2{k}_{F}$ spin and $2{k}_{F}$ charge Fluctuations coexist.
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spin triplet F Wave like pairing proposed For an organic superconductor tmtsF 2 pF 6
Physical Review B, 2001Co-Authors: Kazuhiko Kuroki, Ryotaro Arita, Hideo AokiAbstract:By examining how the spin- and/or charge-Fluctuation exchange can contribute to pairing instabilities, we propose that a spin-triplet F-Wave-like pairing with a d-vector perpendicular to the b-axis may be realized in $(\mathrm{TMTSF}{)}_{2}{\mathrm{PF}}_{6}$ due to (i) a quasi-one-dimensional Fermi surFace, (ii) a coexistence oF ${2k}_{F}$ charge Fluctuations and spin Fluctuations, and (iii) an anisotropy in spin Fluctuations. Fluctuation-exchange study For the Hubbard model conFirms the point (i), while a phenomenological analysis is given For (ii) and (iii). The proposed pairing is consistent with various experiments.
Motohiko Hara - One of the best experts on this subject based on the ideXlab platform.
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S14-2. F Wave and spinal excitability; masseteric contraction or motor imagery enhances ulnar nerve F Wave
Clinical Neurophysiology, 2018Co-Authors: Motohiko HaraAbstract:We tested the validity oF instructing patients to clench the teeth to Facilitate F-Waves recorded From a limb muscle in clinical practice. We explored to study eFFect oF motor imagery and voluntary contraction oF the masseter muscles on F Waves recorded From the First dorsal interosseous muscle in healthy subjects. F Waves were recorded at rest, during motor imagery and during voluntary contraction monitored by a Force transducer to maintain the level at 10% oF maximal eFFort. F-Wave persistence increased From at rest to during motor imagery, and during voluntary contraction. The trial average oF F-Waves increased From at rest to during motor imagery and during voluntary contraction. The F-Wave latency revealed no signiFicant changes. We have previously shown that motor imagery or slight voluntary contraction oF the target muscle enhances F-Wave persistence. The current study indicates the same process involving a non-target muscle can also cause a transient increase in distant motoneuron excitability, similar to Jendrassik maneuver. Central drive directed to the masseteric motoneurons can enhance the excitability oF ulnar nerve anterior horn cells as evidenced by an increase oF trial average oF F-Wave amplitudes.
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EFFect oF motor imagery and voluntary muscle contraction on the F Wave.
Muscle & nerve, 2010Co-Authors: Motohiko Hara, Shinichirou Taniguchi, Jun Kimura, Thoru Yamada, Hiroo Ichikawa, Reiko Fujisawa, Hiroshi Shimizu, Tatsuya Abe, D. David Walker, Ryoji KayamoriAbstract:We tested the validity oF instructing patients to minimally contract the muscle to Facilitate F-Wave recording in clinical practice. In 12 healthy subjects, F Waves were recorded From the First dorsal interosseous muscle at rest, during motor imagery, and at up to 30% oF the maximal voluntary contraction (MVC). F-Wave persistence increased signiFicantly From 32.5 ± 11.9% (mean ± SD) at rest to 58.3 ± 15.2% during motor imagery and 90.0 ± 8.7% during 3% MVC. It then remained the same during stepwise changes to and From 30% MVC beFore decreasing signiFicantly From 80.8 ± 18.5% during 3% MVC to 48.7 ± 23.8% during motor imagery and 27.0 ± 16.0% at rest. The trial average oF F-Wave amplitude showed a similar pattern oF Facilitation. Motor imagery enhances F-Wave persistence and amplitude, which Further increase with a slight muscle contraction and show no additional change with a stronger eFFort. Muscle Nerve, 2010
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eFFect oF motion imagery to counter rest induced suppression oF F Wave as a measure oF anterior horn cell excitability
Clinical Neurophysiology, 2008Co-Authors: Shinichirou Taniguchi, Jun Kimura, Thoru Yamada, Hiroo Ichikawa, Motohiko Hara, Reiko Fujisawa, Hiroshi Shimizu, T TaniAbstract:Abstract Objective To test iF motor imagery prevents the rest-induced suppression oF anterior horn cell excitability. Methods Ten healthy subjects underwent two separate experiments, each consisting oF stimulating the median nerve 100 times and recording F-Waves From abductor pollicis brevis (APB) in three consecutive sessions: (1) aFter muscle exercise to standardize the baseline, (2) aFter immobilization oF APB For 3 h and (3) aFter muscle exercise to check recovery. We instructed the subject to volitionally relax APB in experiment 1 (relaxation task), and to periodically simulate thumb abduction without actual movement in experiment 2 (imagery task). Results F-Wave persistence and amplitude declined aFter relaxation task and recovered quickly aFter exercise, but changed little with imagery task. F-Wave latencies showed no change when analyzed individually. The Frequency distribution oF collective F-Waves recorded From all subjects remained the same aFter relaxation task, but showed a shiFt toward longer latencies aFter imagery task. Conclusions Mental imagery without overt motor output suFFices to counter the eFFect oF sustained volitional muscle relaxation, which would, otherwise, cause a reversible reduction in anterior horn cell excitability. SigniFicance This Finding documents the importance oF central drive For spinal excitability, which aFFects F-Wave studies oF a paretic muscle.
Morris A. Fisher - One of the best experts on this subject based on the ideXlab platform.
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Deterministic recurrences oF sequential F-Wave latencies.
Neurology neurophysiology and neuroscience, 2006Co-Authors: Morris A. Fisher, Chawla J, Charles L. WebberAbstract:PURPOSE Historically, F-Waves have been classiFied by various linear descriptors like persistence, latency, duration, amplitude, chrono-dispersion and number oF repeater Waves. But because physiological signals are notoriously nonlinear in nature, the objective oF this study was to apply modern nonlinear methodology to F-Waves sequences to assess the presence oF underlying deterministic structures. Subtle changes in these sensitive markers could give early warnings For neurological problems. METHODS F-Waves were elicited in the leFt abductor pollicis breivs muscle by supra-maximally stimulating the median nerve percutaneously at the wrist. Approximately 200 stimuli were applied (0.5 Hz) to three subjects For at least Four trials each. F-Wave latencies were measured and assembled into sequences in proper order. Recurrence quantiFication analysis (RQA) was applied to these F-Wave sequences From diFFerent dimensional perspectives. Controls were constructed by randomly shuFFling the ordered sequences. RQA has a theoretical mathematical Foundation and practical perFormance record on numerous other physiological systems. RESULTS Recurrence analysis showed that sequential F-Waves Form recurrent patterns with parallel trajectories with deterministic and laminated structures. These Features could be destroyed by randomizing the sequential orders oF F-Waves, upholding the hypothesis that sequences oF F-Waves are deterministically Formed From underlying physiological rules. CONCLUSIONS F-Wave time series are Fully amenable to recurrence analysis which provides a higher-dimensional perspective on the physiological dynamic. The recurrent patterns are complex, but not random, meaning that physiological rules dominate the sequence oF F-Waves. Disease processes within the central or peripheral nervous system may alter F-Wave patterns. IF so, RQA potentially may be a diagnostic tool to help discern subtleties between altered deterministic rules operating in disease.
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Comparison oF automated and manual F-Wave latency measurements
Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology, 2005Co-Authors: Morris A. FisherAbstract:Objective: F-Waves are well-established clinical neurophysiological studies. F-Wave analysis is now cumbersome limiting the useFulness oF F-Waves. This study evaluates the accuracy and reliability oF an automated analysis method For F-Wave latencies. Methods: F-Waves Following 20 supramaximal stimuli recorded From the extensor digitorum brevis muscle oF 80 limbs (55 subjects) were analyzed. F-Wave latencies were determined using a computer program developed by NEUROMetrix (Waltham, MA). These results were compared in a blinded Fashion with manual measurements oF the same datasets by a clinical neurophysiologist with established expertise in F-Waves. The manual measurements were repeated once. Results: The yield rate oF automated median F-Wave latencies was 100% with a correlation coeFFicient (CC) oF 0.996 when compared with manual assignment results. For individual F-Wave latency measurements, comparable values were 90% and 0.977, respectively. The repeated manual measurements revealed a yield rate and CC For median latencies oF 100% and 0.998, respectively, with comparable values For individual latency measurements oF 95% and 0.992. Conclusions: These results indicate the Feasibility oF a reliable computerized automated analysis oF F-Wave latencies. SigniFicance: A reliable automated analysis oF F-Waves should add meaningFully to the value oF these responses in clinical neurophysiology.
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The contemporary role oF F-Wave studies. F-Wave studies: clinical utility.
Muscle & nerve, 1998Co-Authors: Morris A. FisherAbstract:Keywords: F Waves; peripheral neuropathies; radiculopathies; nerve injury; F-Wave utility
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Normative F Wave values and the number oF recorded F Waves
Muscle & nerve, 1994Co-Authors: Morris A. Fisher, Bruce Hoffen, Cheryl HultmanAbstract:F Waves were recorded From the right abductor pollicis brevis oF 11 normal subjects Following 100 supramaximal stimuli. F Wave data From sequential groups oF 10 stimuli were analyzed. "True" values were considered those based on the results Following all 100 stimuli. The F Wave data evaluated were: minimal, mean, and median latencies; persistences (the percentage oF F Waves present in a series oF stimuli); chronodispersion (CD) (the diFFerence between minimal and maximal F latencies); mean F/M Wave (mF/M) amplitudes; and repeater Waves. F latencies appear normally distributed, and there is no statistical justiFication For using either median latencies or amplitudes. Following 10 stimuli, however, mean latencies are more reproducible than minimal values. In these normal data, results Following 10 stimuli give latency measurements within 1 ms oF "true" as well as For persistences; 20 stimuli will provide mean latencies within 0.5 ms oF "true" as well as probable reasonable values (i.e., 80% oF "true" or greater, For mF/M and the percentage oF repeater Waves; For CDs 80% oF "true" or greater, 50-60 stimuli are needed; For the number oF individual repeater Waves, data From all 100 stimuli would be required. Analysis oF repeater Waves amplitudes would support a preFerential activation oF larger motor units in F Waves.
Björn Falck - One of the best experts on this subject based on the ideXlab platform.
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ReFerence values oF F Wave parameters in healthy subjects
Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology, 2003Co-Authors: Leena Puksa, Erik Stålberg, Björn FalckAbstract:Abstract Objective and Methods : A large reFerence value database For F Wave parameters was constructed with data From 121 to 196 healthy subjects; the age range oF the subjects was 14–95 years. We studied the Following parameters: minimum F Wave latency (FMINLAT), mean F Wave latency (FMEANLAT), maximum F Wave latency (FMAXLAT), number oF F Waves/20 stimuli (FNUMBER) and F Wave dispersion (FDISP=FMAXLAT-FMINLAT). The median, ulnar, peroneal and tibial nerves were studied. Results : Height explains almost halF oF the FMINLAT variability. The F Wave latency increases with height in the arms by 0.2 ms/cm and in legs 0.4 ms/cm. The eFFect oF age on F Wave latency in the arms is relatively small, only 0.03 ms/year; and in the legs age increases the FMINLAT by 0.1 ms/year. Gender does not aFFect FMINLAT in a systematic way. The peroneal nerve has slightly longer FMINLAT than the tibial nerve, while the FNUMBER is higher in the tibial nerve than the peroneal nerve. The diFFerences between the ulnar and median nerve are slight. There is a very high correlation between all 3 latency parameters (FMINLAT, FMAXLAT and FMEANLAT), but no correlation between FDISP and FNUMBER and the other parameters. Side to side comparisons reveals no signiFicant diFFerences in any oF the parameters except For the median nerve FMINLAT and FMEANLAT, which is 0.2 ms longer on the right than leFt. IF side diFFerence oF more than 2 standard deviation is taken as the upper limit For normal, the side diFFerence in arms is 1.4 ms and in legs 3 ms. In repeated studies the interexaminer variability is small; the correlation coeFFicient between the diFFerent F parameters is high ( P >0.6 in arms and P >0.7 in legs). In the arms the upper limit For a signiFicant diFFerence oF FMINLAT on repeated studies in the median nerve is 1.0 and 1.7 ms For the ulnar nerve. In the legs, FMINLAT For the peroneal nerve is 2.6 ms and For the tibial nerve is 2.1 ms. Conclusions : This large reFerence value database can be used not only to evaluate single measurements in relation with height and age, but also to compare right and leFt side and changes over time at repeated studies.
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F Wave latency the most sensitive nerve conduction parameter in patients with diabetes mellitus
Muscle & Nerve, 1997Co-Authors: Henning Andersen, Erik Stålberg, Björn FalckAbstract:In this study we examined the diagnostic sensitivity oF minimal F-Wave latency, F-Wave persistence, motor nerve conduction velocity (MCV), and amplitude oF the compound motor action potential (CMAP) oF the median, ulnar, tibial, and peroneal nerves, and oF sensory conduction velocity (SCV) and sensory nerve action potential (SNAP) amplitude oF the sural nerve in 82 diabetic patients. For the median, ulnar, and tibial nerves the Z scores oF the minimal F-Wave latency were signiFicantly larger than those oF the MCV, and For all Four motor nerves the Z scores oF the minimal F-Wave latency were signiFicantly larger than those oF the amplitude oF the CMAP. The Z scores oF the peroneal minimal F-Wave latency exceeded those oF peroneal MCV, sural SCV, and sural SNAP. F-Wave persistence did not diFFer signiFicantly From the reFerence values. In conclusion, minimal F-Wave latency is the most sensitive measure For detection oF nerve pathology and should be considered in electrophysiological studies oF diabetic patients.